Opacity sensors typically work with a special infrared light source,
and can be used for applications such as verifying the opacity of
containers and packaging films, checking the turbidity or clarity
of solutions, and measuring relative light transmission for other purposes.
These sensors allow high-speed in-line measurements in real time.

Color sensors are used in similar pass/fail applications where
the product characteristic being measured is its color. A typical
application is verifying the proper color of a translucent container,
which helps identify the manufacturer or product.